coleman



C. l COLEMAN. POLISHING MACHINE. APPLICATION FILED nun: 22. 1915.

1,318,260. Patented Aug. 19, 19195 E ETS-SHEET l.

; Aria/Mrs C. J. COLE-MAN. POLISHING IACHINE. APPLICATION min JUNE 22. 1915.

1,313,260.- PatenmdAug. 19,1919.

4 SHEETS-SHEET 2- {m pa Q 33 i l| gs g 2 i Q A TTOHNEY8 0.1. COLEMAN.

PousHmc momma.

APPLICATION FILED JUNE 22.1915.

1,313,260. Patented Au 19, 1919.

4 SHEETS-SHEET. 3.

INVENTOR sr 7 42mins C.-J. COLEMAN.

POLISHING MACHINEr. APPLICATION m 22. |9|5.

1,313,260. PatentedAug. 19,1919;

'4 SHEETS-SHEET 4.'

' II as UNITED STATES PATENT OFF1CE.

. CLYDE J. COLEMAN, OF NEW ROCHELLE, NEW YORK ASSIGNOB TO STERN-COLEMAN DIAMOND MACHINE COMPANY, INC., OF NEW YORK, vN. Y.

POLISHING-MACHINE.

Specification of Letters latent.

Application filed June 22, 1915. Serial No. 35,511.

polishing gems or subjecting them to abra' sive treatment.

The polishing of gems or .precious stones requires great precision and the greatest skill has been required. The main object of the present invention is to provide an improved machine which is largely automatic, so that attendants with little skill in the art may by the use of the machine, polish gems with great accuracy and precision and in a minimum of time, and is also simple and efficient in operation and construction, permitting of easy adjustment of the stone in its various desired positions. The machine being automatic. one attendant may operate or watch several machines at a time, so that not only is highly skilled labor unnecessary, but one attendant may do the work heretofore required of several. The various novel features and combinations will more clearly appear from the following description and a pended claims, taken in connection with t e accompanying drawings.

In the drawings Figure 1 is a side View of a machine embodying my improvements in a preferred form. Fig. 2 is a plan view thereof. Fig. 3 is an end view thereof. Fig. 4 is a similar view certain parts being broken away or shown in section to more clearly illustrate the operation. Fig. 5 is a section taken on the line 5,5 of Fig. 4. Fig. 6 is a section taken on the line 66 of Fig. 5. Fig. 7 is asection taken on the line 77 of Fig. 4. Fig. 8 is a partial view of the tripping mechanism similar to that of Fig. 4. but looking in the opposite direction. Fig. 9 is a detail end View of parts shown in Fig. 8'. Fig. 10 is a longitudinal section of the do and gem holder. Fig. 11 is a ection ta en on the line 1111 of Fig. 1 Fig. 12 is an enlarged section taken on the line 1212 of Fig. 2. Fig. 13 is a section taken on the line 13-43 of Fig. 12. Fig. 14 is a diagram illustrating the position of the gem with respect to the dop arc, and

Fig. 15 is a detail view showing the method of securing the stone to the arbor.

Referring to the drawings, 1 represents a suitable rotating polishing lap, carried by the spindle 2. The diamond or other precious stone 3 issecured 'in an arbor 4, by means of a suitable cement 3' or in'any other suitable or well known manner. The cement is used in considerable body inthe recess in the end of the arboras shown in Fig. 15, a hole 4 being provided through which a pin or tool may be driv n from the outside to loosen the cement an stone and dislodge them from the arbor after polishing all the facets on one side of the girdle;

but is prevented from rotation therein by' means of a key 6 (see also Fig. 11), so that the arbor may always be inserted in the dop in the same rotative position'with respect thereto, whereby the stone will properly register with the index pointer 9. hereinafter referred to. The dop spindle 5 is rotatably mounted in a dop spindle 7, the spindle 5 having secured on its upper end a knurled hand nut 8, having an integral pointer 9, cotiperating'with a circular index scale 10 on the beveled upper edge of the dop spindle 7. Upon rotating the knurled nut 8, the spindle 5, together with the arbor 4 is rotated in the dop spindle 7, in order to bring the various facets of the diamond parallel with the polishing surface of the lap, in order that they may be polished. For the purpose of adjusting the arbor 4, together with the m carried thereby, lon itudinally along t e axis of the dop spin e. the dop spindle has arranged centrally therein a rod 11 engaging a screw 12, integral or rigid with the arbor 4.- At its upper end the rod 11 is provided with a rigid or integral screw-threaded portion12, upon which is screwthreaded a small knurled nut 13 and a lock-nut 14. Upon turning the nut 13 relative to the dop spindle 7, the arbor 4. nut 8 and spindle 5, the rod 11 is turned relatively thereto, and operating upon the screw 12, causes thearbor 4 to be moved slowly longitudinally to the dop spindle 5. The dop spindle 7 has arranged integral or rigid therewith an extension 15, carrying Patented Aug. 19, 1919.

an arcuate rack 16. slidable in an arcuate adjust the axis of the dop and the gem with regard to the polishing surface, the arcuate rack 16 is moved in the arcuate guide 17, in various positions, in the Well known manner. In order that this movement may be carefully regulated, the arm 18 contains a worm l9, operated by a thumb piece 20, the worm 19 engaging with the teeth of the rack 16, so that upon turning the thumb piece 20, the rack is slowly moved along the guide 17, so as to adjust the axis of the gem to various angles with res eet to the polishing surface.

It is desirab e that the gem be arranged so that the center of its girdle coincide with the center of the arc of the arcuate rack and arcuate guide. This can be accomplished by operating the nut 13, in order to adjust the arbor 4 with the gem 3 longitudinally to the dop spindle, so that in whatever position the dop spindle 7 may be, the center of the girdle of the gem will coincide with the center of the dop are as well as lie. in the axis vertical to the polishing'surface about which the dop spindle 7 is rotatable, as will hereinafter more clearly appear.

As illustrated in Fig. 14, the girdle of the gem 3 is shown at 21, and the center of the girdle is indicated at 22. This center 22 coincides with the center of the dop are,

or the arc of the arcuate guide 17, which is indicated by the line 23. As shown in Fig. 14, one of the angular facets 24 is in posltion to be polished.

The supporting arm 18 is rotatable on the spindle 25, the axis of rotation passing through the center of the dop arc and center of the girdle of the gem as just explained. This arm 18 carries an index 26, coiiperating with a pointer 27 fixed on the spindle 25, for the purpose 'of indicating the angle to which the spindle 25 and gem 3 are turned. The spindle 25 is carried by a polishing head 28, which, in turn, is slidably mounted upon a horizontal cylindrical supporting member 29. The polishing head 28 may be oscillated about an are upon the horizontal cylindrical member 29, through a part of a circle, in order that the polishing head may be rocked in order that the stone may be lifted from the polishing lap and inspected from time to time, without difficulty. The head 28 is held in proper vertical position with the stone on the polishing surface by coming in contact with a stop 30 fixed to the member 29. A clamping screw 31 is provided in the head 28 for the purpose of lockin the head in any desired position. That 1s, the head 28, upon the clamping screw 31 being loosened, may be shifted radially on the member 29 to bring the; gem onto difierent polishing bands of the lap and then locked in any such desired position with the gem against" the polishing surface. Or, also, upon loosening the lock screw 31, the head 28 may be oscillated, rotating the dop spindle 7 and the gem carried thereby upwardly for inspection or adjustment of the dop and the parts locked in this position by means of the set screw 31. Upon releasing the set screw 31, the head 28 may be oscillated back again to bring the gem against the polishing surface and which will bring the gem back against the lap in the same position as before, so that no new adjustment is required.

The spindle 25 is likewise movable vertically or longitudinally along its axis in the polishing head 28, and carries at its upper end an adjustment nut 32, having a beveled face 33, cooperating with scale marks 34, on the upper end of the spindle 25. A collar fitting about a recessed portion of the adjusting nut 32 has an arm 35, having a downwardly extending rack 36, operatively engaging a pinion 37, on a shaft 38 (see Fig. 12) journaled in an upward extension 39 on the polishing head 28. At its other end the shaft 38 has rigidly secured thereto a toothed wheel 40. For this purpose, a pin 41 passes through a collar 42 surrounding an integral collar 43 on the toothed wheel 40, and the shaft 38. Pivoted about the collar 43, between the collar 42 and the toothed wheel 40 is an arm 44, carrying an adjustable weight 45 thereon. The arm 44 is provided with a spring pressed pin 46 adapted to engage the teeth of the toothed wheel 40, so that as the rack 36 moves downwardly, being carried downwardly as the spindle 25 moves downwardly, as the face of the gem being polished wears away, the gear 37 is permitted to turn, thereby permitting the shaft 38 to turn. Normally the arm 44 is adjusted to such position relative to the toothed wheel 40 and shaft 38 that at the commencement of the polishing operation the arm 44 extends upwardly, nearly to the vertical. ;Then, as the polishing proceeds, the arm swings downwardly, as illustrated in Fig. 1. The weight 45 tends to rotate the toothed wheel 40, shaft 38 and gear 37, to pull the rack 37 downwardly, thereby causing the gem 3, which is ultimately carried by the spindle 25, to be pressed against the polishing surface, and, as the facet of the gem is polished away, thereby increasing its area, the pressure with which it is forced against the polishing surface is incrcasedby reason of the arm 44 swin ing outwardly, more near to the horizonta so that the weight 45 acts with reater leverage. Thus, as the gem is polished, and its facet worn away, it is pressed against the polishing surface with a gradually increasmg pressure.

In order to indicate the polishing operation, and show that the correct grain relation of the stone is presented'to the lap, there is secured to the toothed wheel 40 a eollar 46, having integral therewith a gear 47, which meshes with a gear 48, fixed to a stud shaft 49, which stud shaft also has fixed thereto a large gear 50, meshing with a small gear 51, on a stud shaft 52, extending through a casing 53, formed on the upper the pointer 54, which indicates on the ,dial.

55 the amount of polishing that has taken place. The operator may thus tell not only how. rapidly the polishing. of any facet is proceeding, but also when it is nearly finished. v j

The gear 50 also meshes with a gear 56, carried on a stud shaft 57, which shaft has I fixed thereto a larger gear, meshing with a small gear 59 on a stud shaft 60, which stud shaft has secured thereto a larger gear 61, which'in turn meshes with a small gear 63 on a stud shaft 64. The stud shaft 64 has fixed thereto a cam65, arranged eccentric to the shaft 64 and operating in a slot 66 in a weight member 67 pivoted to the casing 53 at 68. The outlineof the weight member 67 is shown irregular in order to accommodate and be spaced from the various gears and shafts. A cap plate 69 is attached to the back of the casing 53, to cover up the various gears just mentioned.

The purpose of the weight member 67 is to prevent too rapid approach of the gem onto the polishing surface. Thus after the gem has been put in place in the dop spindle 7, with the spindle, 25 raised, and when it is desired to proceed with the polishing,

the spindle 25-is permitted to drop, so that the gem is brought down against the polishing lap 1. The lowering of the spindle 25, however, causes the downward movement of the rack 36 and the rotation of the gears within the casing 53, which causes the cam 65 to very rapidly oscillate the weight 67 about its pivot 68, which, in this manner, acts as a'retarding means to cause the gem to approach the polishing lap slowly, so that it will not be injured.

Ri 'dly secured to the adjusting nut 32, in a -shaped groove therein, is a collar 69, carrying a downwardly-extending arm 70, having integral with its bottom a frame member 71. The collar 69 may be made in two pieces, clamped together by a screw 72 (see Figs. 1 and-3'). Pivoted in the frame piece 71 is a lever 73 having an outerend 74 and an inner end 75 normally pulled downwardly by spring 76. (see Figs. 8 and 9). The end 75 may be held in an upper position by means of a catch 77 on a tripping lever 7 8, pivoted to the frame piece 71, at 79. The trip lever 78 is made in two pieces, the lower piece 80 comprising a foot which hangs down in close proximity to the polishing surface of the lap, which may be adjusted with respect to the upper part of the lever by means of a set screw 81. When the foot 80 engages the rotating lap, as will more fully be hereinafter .cxplained. the catch 77 slips from beneath the nut 75, thereby permitting the spring 76 to act upon pivot arm 73, causing its end 74 to move upwardly and engage an insulating contact arm 82, carried upon, but insulated from the stop 30, so as to close an electric circuit, as will be more fully described hereinafter. The trip lever 78 is also provided with an upwardly extending catch 83, adapted to engage the underneath side of one end 84 of a lever 85, pivoted in the frame piece 71 by pivot 86 (see Fig. 4). Pivoted to the lever 85, near the pivot 86, is a link 87, sliding through a frame piece 88 and carrying at its upper end a roller 89 engaging the under-v neath side of a flange cup 90, in which is arranged a coil spring 91, one end of which abuts against the bottom of the cup 90, and the other end of which abuts against the underneath side of the adjusting nut 32, so as to tend to separate these two. When the trip lever 78 is rocked sufficiently so that the catch 83 slips off of the end 84 of the lever 85, allowing the lever to drop downwardly together with the link 87 and roller 89, then the cup member 90 is permitted to drop downwardly upon a collar 92, so that then the spring acts as if directly upon the collar 92 on the polishing head 28 and causes the adjusting nut 32 to be raised relatively to the head 28. The raising of the nut 32 relative to the head 28 causes the spindle 25, upon which it is screw-threaded, to be raised and with it the arm 18, dop spindle 7 and gem 3, so that when the trip lever 78 is swung sufficiently to slip off of the end 84, the spring 91 acts to'raise the gem and withdraw it from the polishing surface. The collar 92 is recessed as at 93 (see Fig. 5) to form guideways, to accommodate downwardly-extending guide members 95 carried integral with the adjusting nut 32 (see also Fig. 6).

96 represents a suitable stand, carrying a spindle 97 adjustable therein by means of a thumb screw 98; and carried upon the spindle 97 is a horizontal arm 99 to which is secured an electric motor 100. The motor 100 is adapted to drive a worm 101, meshin with a worm gear 102, on a shaft 103, which shaft carries a suitable cam (not shown) operating a link 104, the outer end of the link 104 being pivotally connected to the horizontal cylindrical member 29 at105 (see Figs l and'2), so that when the motor 100 is energized, it drives the worm 101, which in turn drives the gear 102, which in turn reciprocates the link 101, which in turn reciprocates the horizontal cylindrical member 29, causing it to slide back and forth on the arm 99, and reciprocates the gem radially on the polishing lap. The motor 100 is so connected that when the end 74 is thrown upwardly by the spring 7 6 to contact with the contact member 82, as previously explained, the motor is energized and the reciprocation of the member 29 together with the polishing head 28 and the gem carried thereby is started.

The levers 73 and 85, together with adjacent parts, are covered by means of a casing 106, which casing, however, is provided with a slot 107, through which extends a handle 108, which handle is rigidly secured to the lever 85 (see Fig. 4).

When the handle 108 is lifted, the trip lever 78 swings in such manner that the catches 77 and 183 swing beneath the outer ends and 8-1 respectively. The foot of the trip lever 78 has two portions struck on arcs of different radii from the point 79 about which the trip lever 78 is pivoted. The first portion 109 is struck about the greater radius while the second portion 110 is struck about the lesser radius.

In operation the gem is suitably attached to the arbor 1, which is then placed in the spindle 5 and dop spindle 7. In order that the center of the girdle may be placed coincident with the center of the dop are lying in the axis of the spindle 25, a pointer 111 is provided (see Fig. 1) carried upon an arm 112, which may be oscillated in bearings 113 carried on the dop spindle 7. The arm 112 carries a thumb piece 114, by means of which the arm 112 may be oscillated, so that the pointer 111 is brought closely adjacent the gem 3. The gem is then adjusted to bring the girdle opposite the pointer which will place the center'of the girdle coincident with the center of the dop arc. Then the polishing head 28 is slid along the cylindrical member 29 until the gem is brought over the desired polishing band on the la 1, after which the head 28 is locked to the member 29 by means of thumbscrew 31.- Then the spindle 25 is permitted to descend, the descent being retarded by means of the oscillating weight member 67, as previously explained. When the gem 3 has descended into contact with the polishing lap 1, and the lap is rotated, the polishing proceeds. As the facet of the gem is polished away, the pointer 54 indicates not only how fast the polishing operation is g roceeding, but how far it has roceeded. he foot piece 80 is adjusted re ative to the rest of the trip lever 78, so that when the polishin is started it 1sv a slight distance above the po ishing surface.

- The collar 69, arm 70, frame piece 71 and parts carried thereby are adjustable rotadesired that the tably' about the adjusting nut 32 and spindle 25, so that the foot piece 80 may be brought into the path of the gem on the polishing lap.

It is desirable that when the olishing of the facet has been nearly completed to reciprocate the gem radially over the polishing lap for a short time, in order to polish out any streaks which may have been produced in the facet. When the facet has been polished away to the point where it is desired, this reciprocation takes place, the forward part 109 of the foot 80 engages the surface of the lap, so that the rotation of the lap quickly rocks the tri lever, causing the catch 77 to slip off of the end 75, permitting the arm7a to move upwardly and engage the electrical contact member 82 and close the electric circuit to energize the motor 100, which thereupon causes reciprocation of member 29, polishing head 28, and conse quently reciprocation of thegem 3 radially over the polishing surface. This movement of the trip lever 78, however, is not sufiicient to cause the catch 83 to slip off of the end 84 of lever 85. When, however, the polishing has proceeded to the desired extent and it is olishing operation cease and the gem be withdrawn from the polishing lap, the rear of the foot 110, which is at a slightly greater distance from the polish ing surface than the part 109, comes into contact with the polishing surface, by reason of the gradual downward movement of the gem and its carrying spindle 25, and arm 7 0, and frame piece 71 carried thereby, so that then the trip lever 78 is given a further swing and the catch 83 swings off of the end 84, permitting the lever 85 to drop down, carrying down with it the link 87 and roller 89 and permittin the spring 91 to force cup 90 against the col ar 92, and when the spring 91 causes the cup 90 to engage the collar 92, since it can force the cup 90 no farther downwardly, it forces the adjusting nut 32 upwardly, carrying with it the spindle 25 and gem 3, so that the em 3 is quickly withdrawn from the poli 'ng surface and the polishing operation stopped.

When it is desired to reset the apparatus,

the handle 108 (see Fi 2, 3 and 4) 1s.

taken hold of and raise carrying with it the lever 85, and also the lever 73, by reason of the lever 7 3 having an arm 115 which engages over the top of the lever 85, so that as the lever 85 is raised it likewise raises the end 75 of the lever 73. The trip lever 78 then swings back to normal position, causin the catches 77, 83, to swin beneath the ene 75 and 84 and hold the evers 73 and 85 in position for a new'operation.

From the above it will be seen that the inter 111 acts as a sett' indicator for mdicaxting the position of e stone longi- 'tudinally of the axis of the arbor 4 and dop spindle 7 and the thumb nut 13 acts as means for adjusting the arbor longitudinally with respect to its axis to bring the stone into proper relationship'with the'setting indicator, so that the center of the girdle of the stone or the eometric center of the gem is coincident wit the center of the dop arc. and likewise the vertical axis about which the dop.head,-or dop 7 is rotatable, namely the axis of the spindle 25.

It will also be noted that the Weight *5 may be adjusted to various positions along the arm 14, so that the pressure with which the stone is pressed against the lap maybe adjusted at various stages of the polishing operation. I

It will be seen that the stone carrying means, including the dop spindle 7 and head or frame 28, is pivoted to rock on the longitudinal cylindrical arm 29 in'such a manner that it is pivoted about an axis extending substantially parallelto the polishing face of the'lap and so that the carrying means holds the'stone against the lap at one side of the plane drawn through said axis and at right angles to the polishing surface, whereby the stone may be lifted from the lap Without stopping the polishing operation or affecting the adjustment of the stone with respect to the .laplwhen the head is again replaced.

The stand 96 and arm 99 act as a suitable frame for carrying the various parts as above described. When the head 28 is thrown into position with the spindle 25, with its axis at right angles to the polishing surface, it may be locked in this position by means of the screw 31, with the stone against the lap. It will be seen further that the parts which move downwardly as the polishing proceeds may be said to consist of a three-part spindle, comprising the dop spindle'7, the spindle proper 25, and the adjusting nut 32, each of these parts being adjustable one with respect to the other, and means carried onthe first part or dop spindle 7 for carrying the stone to be ground in engagement with the polishing surface of the lap, namely the arbor 1, and means for adjusting thisjcarrying part or arbor 4, comprising the nut 13, and means for adjusting the third part 32 with respect to the second part 25, comprising the screw-threaded portion of the nut 32, and that the index 34 indicates the amount of adjustment between the parts 25 and 32.

The trip member or trigger 78 is preferably arranged to track in the path which the, gem takes on the lap. It may, therefore, be termed a tracker carried by the spindle 25, in the path of the gem on the lap and arranged to engage the lap to be rocked thereby, at a predetermined stageof the polishing operation, whereupon, at

one stage it sets into operation the motor to reciprocate the gem and at another stage sets into operation the spring 91 to withdraw the gem from the polishing surface and discontinue the polishing operation. This withdrawing means acts as a depth gage for automatically determining the depth to which the polishing off of the facet is carried. The arm 18, carrying the parts 15 and 16 and'dop spindle 7 may be termed a polishing head carried by the spindle 25 and arranged to hold the gem 3 in contact with the lap. 'It will be seen that by adjusting the adjusting nut 32, which acts as a micrometer screw carrying the trigger 78 with its foot 80, the trigger 78, 80, may be adjusted longitudinally of the spindle 25 relative to the position of the gem to the lap, in order that it will operate to trip and stop the polishing operation when the facet has been polished to its desired extent. Prior to this tripping, the levers 73 and 85, held up by the catches 77 and 83, act as locking means for locking the resilient spring in compressed condition ready to act to withdraw the gem from the lap when released.

Although I have described my improvements as embodied in a particular machine, it will be understood that many changes and modifications may well be made without departing from the spirit and scope of my invention in its broader aspects. Accordingly, I do not desire to be limited by the details shown and described, except as clearly specified in the appended claims.

,What I claim as new am] desire to secure by Letters Patent is 1. In an apparatus of the class described, the combination of a suitable frame, a carrying-head, a gem-holding arbor carried by the carrying-head, a setting-indicator for in dicati the position of the stone longitudinally o the axis of the arbor and means for adjusting the arbor longitudinally with respect to its axis to bring. the stone into proper relationship with the 'setting-indis cator. p

2. In an apparatus of the class described, the combination of a suitable-frame, a polishing lap, a dop rotatable about an axis perpend cular to the lap and adjustable over an arc angularly with respect to the lap, a gem- -holding arbor carried by the dop, a setting indicator for indicating the position of the stone longitudinally of the axis of the arbox, and means for adjusting the arbor longitudinally with respeet-toits axis to bring the stone into proper relationship with the setting-indicator; V

3. In an apparatus the combination of, a suitable frame, a dop, a gem-holding arbor carried by the dop, an arcuate guide for adjusting the dop and arbor angularly to polish, different facets of the class described,

on the stone, a setting-indicator for indicating the center of the are of said arcuate, guide and means for adjusting the arbor longitudinally of its axis to bring the girdle of the stone in line with said pointer whereby the center of the arc of the arcuate guide may be in the center of the girdle of the stone.

4. In an apparatus of the class described, the combination of a suitable frame, a polishing lap, a dop rotatable about an axis perpendicular to the lap and adjustable over an arc angularly with respect to the lap, a gem-holding arbor carried by the dop, a setting-indicator for indicating the center of the arc and means for adjusting the arbor longitudinally of its axis to bring the girdle of the stone in line with said pointer whereby the center of the are may be in the center of the 'rdle of the stone, the centerof said are a o lying in the vertical axis about which the dop is rotatable. i

5. In an apparatus of the class described, the combination of a moving polishing lap, a supporting member, and a frame extending horizontally over the lap and carrying the stone to be ground against the polishing surface of the lap, said frame being pivoted to rock about an axis substantially parallel to the polishing surface of the lap, whereby upon rotation of said frame the stone may be withdrawn from the lap for inspection, and means for sustaining the frame in its rotated position with the stone withdrawn from the lap.

6. In an apparatus of the class described, the combination of a polishing lap, a suitable frame, an arcuate guide vertically movable with respect to the frame and la' and adapted to be rotated in a plane para lel to the lap, a dop carried by and adjustable along said arcuate guide, a gem-holding arbor carried by the dop, a setting indicator and means for moving and adjusting the gem-holding arbor relatively to the setting indicator to bring the stone into any desired position with respect to the center of the arc of the arcuate guide, means for withdrawing the dop from the lap when the gem has been ground to a predetermined extent and means for adjusting the extent to which the stone may be ground before such withdrawal.

7. In an apparatus of the class described, the combination of a polishing lap, a suitable frame, means carried by the frame for feedin the stone to be ground against the lap, sald means embracing a train of gears operated by the movement of the stone toward the lap and a body adapted to be reciprocated by said gears, whereby the inertiaof'said body causes a slow approach of the stone toward the lap before the stone engages the lap.

8. In an apparatus of the class described, the combination of a polishing lap, a suitable frame, means carried by the frame for feeding the stone to be ground against the lap, said means embracing means for causing the stone to be pressed against the lap with increasing pressure as the grinding proceeds, a train of gears operated by'the ting proceeds and means whereby said pressure may be adjusted at various stages of the operation.

10. In an apparatus of the class described, the combination of a polishing lap, a suitable frame, means carried by the frame for feedingthe stone to be ground against the lap, a train of gears operated by the movement of the stone toward the lap and a pointer operated by said gears and a scale cooperating with said pointer whereby the progress of the grinding operation is indicated.

11. In an apparatus of the class described, the combination of a suitable frame, a polishing lap, a dop rotatable about an axis perpendicular to the lap and adjustable'over an arc angularly with respect to the lap, a gem-holding arbor'carried by the dop and adjustable over the arc with the dop and means for adjusting said arbor with the gem along the axis of the arbor irrespective of its angular, position with respect to the lap.

12. In an apparatus of the class described. the combination of a rotary polishing lap, an arm extending over said lap, means for means, said frame being pivoted on said arm about an axis extending substantially par- 211161 to the polishing face of the lap,'the carrying means holding the stone against the lap at one side of a plane drawn through said axis and at right angles to the polishing surface, whereby the stone maybe lifted from the lap without stopping the apparatus or afl'ecting thev adjustment of the stone carrying the stone against the lap to polish the stone, a frame carrying said carrying to the polishing surface, whereby the stone the lap, means for withdrawing the stone.

from the lap when it has been ground or polished to a predetermined extent, said frame being pivoted to rock about an axis substantially parallel to the polishing face of the lap, the stone being held against the lap at one side-of the plane drawn through said axis and at right angles to the polishing surface whereby the stone may be withdrawn from the lap for inspection without affecting the adjustment of the Stone with respect to said frame.

15. In an apparatus of the class described, I

the combination of a moving polishing lap, a frame extending over the lap, means movable relatively to the said frame and. car-' rying the stone in engagement with the lap to effect the polishing or grinding'of the stone, means for causing a slow approach of the stone toward the, lap, means for withdrawing the stone from the lap when it has been ground or polished to a predetermined extent and means whereby the operator may at will withdraw the stone and its carrying,

means from the lap to inspect the stone and replace the same without affecting the adjustment of the stone with respect to the frame.

16. In an apparatus of the class described,

a three-part spindle, movable in the frametoward and from the lap, each of said parts being adjustable one with respect to another,

means carried by one part of the spindle for carrying the stone to be ground in engagement with the polishing surface of the lap, means for adjusting said carrying part with respect to the second part of the spindle, means for adjusting the third part with respect to the second part of the spindle, an indicating device for indicating the extent to which the grinding has progressed, en-

gaging the third part of the spindle.

18. A gem-polishing machine, comprising a polishing lap, a spindle at right angles to lap.

the polishing surface ofthe lap, an arcuate guide carried by the'spindle and a dop head adjustable'upon said arcuate guide and provided with gem-holding means adapted to hold the eometric center of the gem or center of the girdle at the center of the arcuate guide and in the axial line of the spindle at various positions of the dop head upon the arcuate guide While different facets of the gem are being polished.

19. A gem-polishing machine, comprising a polishing lap, a spindle at right angles to the polishing surface of the lap, an arcuate guide carried by the spindle and a dop head adjustable upon said arcuate guide and provided with gem-holding means adapted to hold the geometric center'- of the gem or the center of the girdle in the axial line of the spindle at various positions of the dop head upon the arcuate guide while different facets of the gem are being polished.

. 20. A gem polishing machine having in combination a, polishing lap, a gem holder for holding the gem in contact with the lap, means for reciprocating the gem-holdmg means and gem over the lap during the polishing -when the gem has been polished to a predetermined extent, means" for discontinuing the polishing when the gem has been polished to a predetermined extent,-

and a single trigger member for causing the actuation of both of said withdrawing means and reciprocating means.

21. A gem polishing machine having in combination a polishing lap, a gem holder for holding the gem in contact with the lap, means for reciprocating the gem-holding means and gem over the lap during the polishing when the gem has been polished to a predetermined extent, means for withdrawing the gem' from the lap when the gem has been polished to a predetermined extent, and a trigger member for causing the actuation of both of said withdrawing means and reciprocating means by the engagement of the trigger member with the 22. A gem polishing machine having in,

combination, a polishing lap, a gem-holding means comprising an arcuate guide and a gem-holding dop adjustable along said guide to present different facets of the gem to the lap, and a worm and cooperating ,rack for adjusting the gem-holding dop along said arcuate guide.

23. A gem polishing machine having in combination, a polishing lap, a gem-holding means comprising an arcuate guide and a gem-holding dop adjustable along said guide to present different facets of the gem to the lap, and a screw device for adjusting thedgem-holding dop along said arcuate gui e.

24. In an apparatus of the class described, the combination of a polishing lap, a frame,

a three-part spindle, movable in the frame toward and from the lap, each of said parts being adjustable one with respect to another in series relation, means carried by one part of the spindle for carrying the stone to be ground in engagement with the polishing surface of the lap, means for adjusting said carrying part with respect to the second part of the spindle,-means for adjusting the third part with respect to the second part of, thespindle, a tripping mechanism engaging the third part of the spindle to be operated by the movement thereof, whereby, when said third part has moved a predetermined distance toward the lap, said tripping .mechanism is operated to withdraw the stone from the lap.

25. In an apparatus of the class described, the combination of a polishing lap, a frame, a three-part spindle, movable in the frame toward and from the lap, each of said parts being adjustable one with respect to another in series relation, means carried by one part of the spindle for carrying the stone to be ground in engagement with the polishing surface of the lap, means for adjusting said carrying part with respect to the second part of the spindle, means for adjusting the third part with respect to the second part of the spindle, and an indicating device for indicating the extent to which the grinding has progressed, engaging the third part of the spindle.

26. In an apparatus of the class described, the combination of a polishing lap, a frame, a three-part spindle, movable in the frame toward and from the lap, each of said parts being adjustable one with respect to another in series relation, means carried by one part of the spindle for carrying the stone to be ground in engagement with the polishing surface of the lap, means for adjusting said carrying part with respect to the second part of the spindle, means for adjusting the third part with respect to the second part of the spindle, an indicating device for indicating the extent to which the grinding has progressed, engaging the third part of the spindle, and means-for adjusting said first-mentioned part of the spindle up and down relatively to said second-mentioned part to adjust the stone with respect to the lap without affecting the reading of said indicating device.

27. In an apparatus of the class described, the combination of an arcuate guide, polishing means, a gem-holding dop adjustable on said guide to present various facets of the gem to the polishing means, a gem-holding arbor carried by the dop, and a screw device for adjusting the gem-holding arbor axially of the dop.

28. In an apparatus of the class described, the combination of an arcuate guide. polishing means, a gem-holding dop ad ustable on said guide to present various facets of the gem to the polishing means, a gem-holding anbor carried by the dop, a screw device for adjusting the gem-holding arbor axially of the dop, and means for adjusting the gem-holding arbor rotatively with respect to its axis.

29. A gem polishing machine,- comprising a polishing lap, a spindle at right angles to the polishing surface of the lap, an arcui ate guide carried by the spindle and a dop head adjustable upon said arcuate guide 7 and provided with gem-holding means adapted to hold the center of the girdle of the gem at the center of the arcuate guide and in the axial line of the spindle at various positions of the dop head upon the arcuate guide while different facets of the gem are being polished.

30. A gem polishing machine, comprising a polishing lap, a spindle at right angles to the polishing surface of the lap, an arcuate guide carried by the spindle and a dop head adjustable upon said arcuate guide and provided with gem-holding means adapted to hold the center of the girdle of the gem at the center of the arcuate guide and in the axial line of the spindle at various positions of the dop head upon the arcuate uide while different facets of the gem are Eeing polished and driving means for rotating said spindle to rotate the gem on the polishing lap.

31. A gem polishing machine, comprising a polishing lap, a spindle at right angles to the polishing surface of the lap, an arcuate guide carried by the spindle and a dop head adjustable upon said arcuate guide and provided with gem-holding means adapted to hold the center of the girdle of thegem in the axial line of the spindle at various positions of the dop head upon the arcuate guide while different facets of the gems are being polished.

32. A gem polishing machine, comprising 110 a polishing lap, a spindle at right angles to the polishing surface of the lap, an arcuate guide carried by the spindle and a dop head adjustable upon said arcuate guide and provided with gem-holding means adapted to 115 hold the center of the girdle of the gem in the axial line of the spindle at various positions of the dop head upon the arcuate ide while different facets of the gem are ing polished and driving means adapted to ro- 120 tatc the gem while in contact with the polishing surface about an axis at right angles to the polishing surface.

33. A gem polishing machine having in combination a rotary polishing lap, a spin- 125 dl e having its axis arranged at right angles to the polishing surface of the lap, an arcuatc guide carried by the spindle, having its center in the axis of said spindle, a dop or gem carrying head adjustably mounted on 130 said guide and adapted to carry the gem with the center of its girdle at the center of the'arcuate guide, at various positions of the dop head on'theguide, means-whereby the may be rotated about an axis at right angles to the polishing surface, and means whereby the gem may "be moved laterally over the polishing surface of the lap to change its position from one polishing band to another.

34. In an a paratus of the class described, a polishing ap, means for holding a gem against the polishing surface of the lap to pohsh the gem, said means including an arbor having a recessed end containing an adhesive for securing the gem to the arbor, and said arbor being provided with a hole extending into the recess through which hole a pm or tool may be operated to dislodge the gem from the arbor.

35. In an apparatus of the class described, a polishing lap, means for holding a gem in engagement with the polishing surface of the la to lpolish the gem, said means having an ar r' aving a recessed end containing anadhesive for securing the gem to the arbor and means whereb the cement and gem may be forced out of e recessed end of the arbor.

3 6. In an apparatus of the class described, a polishing lap, means for holding a em in engagement with the polishing sur ace of the lap to polish the gem, said means comprising a suitable frame, a dop carried. thereby and a gem holdin arbor carried by the dop, the dop and ar r having means.

for re stering one with respect to the otheri justable settin .l ry'mg head carried by-and adjustable along where g the arbor may always be inserte m the 0p in one rotative-position with re-v spect thereto. 7

37. In an apparatus of-theclass described, a polishing lap, means for holding a gem in en ment, with the polishing surface of the lap to polish the gem, means for progressively I ncreasing the pressure with which the stone is applied to thepolishing surface as. the surface area of the facet o the stone being polished is increased, and means for adjust ng or changin the said pressure'during such range of variable pressum. 1

38. In an apparatus of the class'describ'ed, thfiin onlibination .of a sgitapale frame ai 1- IS 2 @Pr y g 0 g arbor carried by the carrying head, an adindicator and means for moving and a justin the gem holding arbor tward the lap relative y to the setting indicator.

39. In an apparatus of the class described,

the combination of a polishirilg lap, a spindle ha its axis perpendic ar to the lap and rotab e in a plane parallel thereto, an arcuate guide earned by said spindle, a car- "gem into proper grinding the combination of a suitable polishing lap,

a carrying head, a gem holding arbor carried by the carrying head, a setting nd cator and means for moving and ad usting indicator,

the gem holding arbor'relatively to the ,set-' ting indicator toward the lap.

41. In an apparatus of the class described, the combination of a olishing lap, a dopcarrying. head, a gem olding arbor carr ed bfy the carrying head, means for withdrawing t e head and stone from the lap when the stone has been ground to a redetermined extent, means for adjusting t e position of the head at which said with rawing takes place, a setting indicator, and means for moving the gem holding arbor toward the lap relatively to the setting indicator to bring the sitlon.

42. In an apparatus 0 eclass described, the combination of a polishing la a suitable frame, an arcuate ide vertica ly movable with respect to t e frame and lap1 and; adapted to be rotated in a lane para el to the a a do carrying hea carried by and adjustable a ong said arcuate guide, a gem holding arbor carried b the carrying, head, asetting indicator an means for moving and adjusting the gem holding arbor relatively to the setting indicatorso as to bring the axial line of said guide substantially in the center of the face of the stone being ground, irres ive of the position of the carrying hea in the arcuate guide. 1

43. In an apparatus of the class described, the combination of a polishing lap, at spindle havin its axis perpendicular to the lap and rotate le in a plane parallel thereto, arcuate guide carried by said spindle, a carrying head carried by, and adjustable along indicator, a stone consaid guide a sett' taining arbor carr i efi by said carrylng head,

means for withdrawing the spindle and carrying head from the lap when the stone has been ground to a redetermined extent, means for adjusting t e position of the s indle at which'said withdrawing takes p ace and means for adjusting the position of the stone and arbor'so as to bring the axial line of the spindle substantially. in the center of the face of the stone 'being'ground, irrespective of the position of the carrying h the arcuate guide.

44. In an apparatus of the, class described, the combination of a polishing la a suitable frame, an arcuate ide vert1c y movable with respect to t e frame and lap and adapted to be rotated in a lane paraflel to the lap, ado carrying hea earned by and adjustable a ong said arcuate guide, a gem holding arbor carried b the carrying head, a setting indicator an means for movin and adjusting the gem holding arbor tower the lap relatively to the setting indicator and means for withdrawing the dop carrying head from the lap when the gem has been ground to a predetermined extent, and means for adjusting the extent to which the stone may be ground before such withdrawal, each of said adjustin means being operatable independently of t e others.

neiaaee 45., In anv apparatus of the class described, the combination ofa polishing lap,- a frame, a main spindle slidably mounted in the frame to move toward the lap and carrying the stone to be polished in engagement with the lap, means for forcing t the la an indicating device connected therewith for indicatin the movement of the spindle and stone wit respect to the lap, and means opposing said forcin means, tending to force the spindle away in lap during the polishlng.

CLYDE a. COLEMAN.

e spindle toward 1 in said 

